The present invention is directed to a carrier for a reticle used in semiconductor manufacturing.
The manufacturing of semiconductor chips is an extremely exacting and difficult process. Each chip has many layers and a reticle or photomask is required for each layer that is printed on the wafer. These reticles should have no contamination or dust, in order to avoid defects in the pattern which is formed on the wafer. Traditionally, light has been shined through the photomask in order to form the pattern on the wafer. However, as the patterns on the wafers have gotten smaller and closer together, it is no longer possible to effectively use regular light to form these patterns. That is, the wavelength of regular light is too long to clearly form such small patterns. In order to extend the use of this process to even smaller patterns, other types of light such as deep ultraviolet (248 nm or 193 nm), vacuum ultraviolet (157 nm) and EXTREME ultraviolet (13.4 nm) are being used or are being considered. However, even this shorter wavelength radiation has limits.
Because of the problem of dust and other impurities landing on the reticle during transport, and the possibility of scratches, it is important to have a protective layer. Typically, a pellicle, which is a membrane, is used for this purpose. The use of such a membrane protects the reticle during the transportation and exposure process. However, the use of the pellicle produces additional problems when shorter wavelength radiation is utilized. The shorter wavelength radiation causes the standard pellicle material to burn off or otherwise be destroyed. Thus, if shorter wavelength radiation is to be utilized, it is necessary to find other ways to protect the reticle from the high intensity radiation without destroying the pellicle.